With stable local oscillators \(\alpha _1, \alpha _2\) , we can measure complex quantity \(\gamma (\tau )\)  from the two-photon interference fringe to achieve stellar interferometry in astronomy. Note that this scheme is similar to homodyne measurement technique in stellar interferometry but photon counting technique is used here to avoid the shot noise problem [1]}. However, this method requires time resolution of the detectors better than coherence time in order to measure \(\gamma (\tau )\)  and thus limits the bandwidth, in a similar way to intensity interferometry [2]}.
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